(1) Field of the Invention
The present invention relates to a rear view mirror assembly, and more particularly to a glare preventive rear view mirror assembly having a liquid crystal cell of guest-host type in which the optical transmittance changes in accordance with voltage applied to the liquid crystal cell.
(2) Description of the Prior Art
A rear view mirror assembly having a liquid crystal cell of guest-host type has recently been introduced for the automotive use. The mirror assembly has a flat mirror plate attached to one side of the liquid crystal cell or positioned behind the cell. The transmittance of the cell varies with the change of voltage applied to the cell.
An amount of light impinging on the mirror, however, depends on conditions surrounding the automotive vehicle, that is, the amount of light varies with the position of the following vehicle or the type and kind of headlamps of the following vehicle. Accordingly the transmittance of the liquid crystal cell must be adjusted whenever the amount of light impinging on the mirror changes. Further the transmittance of the cell unavoidably undergoes changes because of dimensional deviation caused during manufacturing process, the influence of the ambient temperature or deterioration from aging. These conditions render it difficult to get enough glare preventive effect from the mirror.